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    DateTue, 9 Jan 2007 23:09:40 +0100
    Subjectmmap / mtime updates
    FromMarek Michalkiewicz <>
    Hello,
    
    What is the current status of the bug where modifications to file
    contents made via mmap fail to update mtime of the file?
    
    This was discussed a few months ago in this thread:
    
    http://lkml.org/lkml/2006/5/17/138
    
    where patches have been posted, but it seems that no final solution
    has been agreed on and applied to the kernel tree.  Updating ctime
    and mtime appears to be required by the standard:
    
      http://www.opengroup.org/onlinepubs/009695399/functions/mmap.html
    
      The st_ctime and st_mtime fields of a file that is mapped with
      MAP_SHARED and PROT_WRITE shall be marked for update at some point
      in the interval between a write reference to the mapped region and
      the next call to msync() with MS_ASYNC or MS_SYNC for that portion
      of the file by any process.
    
    and failing to do it can lead to potential data loss as well, if
    modified files are not backed up (I'm seeing the problem with Samba
    tdb files not being backed up by rsnapshot, for example).
    
    Thanks,
    Marek
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